This site consists of a sand spit and marsh along Green Bay, on the mouth of the Menominee River, and contains Green Bay’s only true dune complex, a system of sand ridges and dunes resulting from wave action and sand deposition, on the bar’s eastern edge. The sand spit shelters a lagoon and large area of shallow water with emergent vegetation. The site encompasses Seagull Bar State Natural Area.
This site is considered critical habitat for the federally endangered piping plover. Piping plovers nested here in 2001 for the first time in 50 years, although the nest failed due to predation and there have been no attempts since. The site is also a major migratory stopover site, attracting hundreds, sometimes thousands, of shorebirds depending on water levels in Green Bay, and diving ducks congregate in the area, particularly during severe weather.